Intramedullary (IM) nails are implantable devices used to stabilize fractures and allow for bone healing. IM nails are inserted into the medullary canal of the long bones of the extremities, e.g., the femur, tibia, or humerus. Currently-used IM nails have a head region that generally includes at least one hole, transverse to the longitudinal axis of the nail, for receiving anchoring means, such as a screw, to secure the nail within the medullary canal of the bone.
Reference is made to FIG. 1, which is a schematic illustration of a targeting device 10, as known in the prior art. Targeting device 10 is used to align one or more IM anchoring screws (not shown) with transverse holes 12 of an IM nail 14, by inserting the IM anchoring screws and/or a drill bit through corresponding aligned transverse holes 16 in targeting device 10. IM nail 14 is inserted into a medullary canal, and targeting device 10 is attached to a proximal end 18 of the IM nail, typically by a screw 20. Screw 20 is inserted into a screw hole 22 at the time of attachment of targeting device 10 to IM nail 14, such that a proximal end 24 of the screw is readily accessible from outside the screw hole. A conventional screwdriver 26 is typically used to tighten screw 20 into IM nail 14.
It is typical to take radiographic images, such as X-ray or fluoroscopic images, during the IM nail implantation procedure, in order to check the alignment of the IM anchoring screws before drilling through the bone. At least a portion of targeting device 10 typically comprises a radiolucent material, such as carbon, in order to minimize the interference of the targeting device with the radiographic images. Screw 20, however, typically comprises a radiopaque metal. Although metal interferes with the radiographic imaging, its use is considered necessary to provide strong coupling between targeting device 10 and IM nail 14.
U.S. Pat. No. 6,183,477 to Pepper, which is incorporated herein by reference, describes an attachment tool for attaching a drill guide to a medical implant such as an intramedullary nail. The attachment tool includes a first end and a housing. The first end includes a first opening that allows a fastener to pass through and thread into the implant, thereby attaching the tool. The housing includes a second opening whose longitudinal axis is preferably offset from the longitudinal axis of the first opening. The housing also includes a guide surface with a groove for directing a driving tool to the second opening. The driving tool is inserted through the second opening to drive the fastener. The driving tool can be inserted and removed during the procedure. The housing also includes a plurality of holes that can be used as drill guide holes or to attach separate drill guides or other orthopedic devices.
U.S. Pat. No. 5,334,192 to Behrens, which is incorporated herein by reference, describes a targeting device for attachment to an implant for treating fractures, such as an intramedullary nail. The targeting device has a targeting arm that extends substantially parallel to the nail, and has a plurality of targeting bores for receiving a drill sleeve, such targeting bores extending at different angles with respect to the axis of the targeting arm.
European Patent EP 0 257 118 B1 to Grosse et al., which is incorporated herein by reference, describes an intramedullary femur nail, and a femur neck screw retained and guided in a transverse throughbore of the femur nail.
U.S. Pat. No. 5,176,681 to Lawes et al., which is incorporated herein by reference, describes an intramedullary intertrochanteric fracture fixation appliance comprising an intramedullary rod having an angulated opening to receive a femoral neck screw. The rod has a co-axial bore extending into the angulated opening, and anti-rotation means located in the bore to selectively prevent rotation of the neck screw in the rod. The open end of the bore is provided with means to positively locate a removable fitting device on the proximal end of the rod, and so that the anti-rotation means can be operated with the fitting device in position.
U.S. Pat. No. 6,656,189 to Wilson et al., which is incorporated herein by reference, describes a radiolucent aiming guide for locating and drilling through the holes in the distal end of an implanted intramedullary nail. The aiming guide comprises an elongate handle constructed substantially of a radiolucent material, which does not cast a strong image on a monitor when exposed to radiation. The radiolucent handle is used in conjunction with a protection sleeve, trocar, drill sleeve, and drill bit, which are used to locate and drill through the hole in the nail. Radiopaque components in the distal end of the protection sleeve, trocar, and drill bit are used to align the drill over the nail hole. A pair of radiopaque pins, located within the handle and lying parallel to its longitudinal axis, aid in ensuring the proper rotational alignment of the aiming guide over the nail hole. The aiming guide may also include a structure to facilitate its alignment over a second hole in the distal end of the intramedullary nail.
U.S. Pat. No. 5,728,128 to Crickenberger et al., which is incorporated herein by reference, describes a femoral neck anteversion guide for use with a femur having a prepared intramedullary canal. The guide includes a radiolucent stem having a distal end for inserting into the prepared intramedullary canal, and a radiopaque angle locator wire embedded within the stem at a known angle for allowing the femoral neck angle and femoral neck anteversion to be determined. The femoral neck anteversion guide preferably includes a handle, which is attached to the radiolucent stem by a radiolucent screw.
U.S. Pat. No. 5,403,321 to DiMarco, which is incorporated herein by reference, describes a radiolucent drill guide for connection to the proximal end portion of an intramedullary nail for aligning a drill with bores of an intramedullary nail when the nail is surgically positioned within an intramedullary canal of a patient. The drill guide includes a handle member of radiolucent material and a guide barrel embedded within the handle. The handle includes an inner generally cylindrical bore and an outer surface that is bonded to closely surround the radiolucent material of the handle member so that the barrel does not rotate freely relative to the handle. The guide barrel includes flanges for preventing relative movement of the barrel in the direction of the central longitudinal axis of the bore of the barrel. A plurality of openings in the handle are at positions spaced away from the barrel for guiding drills when the barrel is affixed to the intramedullary nail so that the drills align with selected openings of the intramedullary nail.
U.S. Pat. No. 5,178,621 to Cook et al., which is incorporated herein by reference, describes a targeting device that includes a radio-transparent handle and a metal snap fit barrel. The radio-transparent handle reduces obstructions in the radiographic image to provide a clearer image to the surgeon for proper placement of the locking screws. The metal snap fit barrel is retained in the handle by an interference fit between the handle and biased keys carried by the barrel.
U.S. Pat. No. 4,827,917 to Brumfield, which is incorporated herein by reference, describes an IM system including a screw and an intramedullary rod. The screw has a threaded portion and a smooth portion, and the rod has a head, stem and a longitudinal bore. There is at least one pair of coaxial holes through the stem, transverse to the longitudinal axis of the rod, for receiving first anchoring means, such as a nail, screw or bolt, to secure the rod within the marrow canal of the femur. There are at least a proximal pair of coaxial holes and a distal pair of coaxial holes in the head of the rod in an angled direction toward the femoral head relative to the longitudinal axis of the rod. The distal pair of head holes are adapted to slidingly receive the screw so as to permit the threaded portion of the screw, in use, to engage the femoral head and to allow sliding compression of a femoral neck or intertrochanteric fracture.
U.S. Pat. No. 5,032,125 to Durham et al., which is incorporated herein by reference, describes an IM hip screw that includes an IM rod, a lag screw and a sleeve for slidably receiving the lag screw. The sleeve is received in a passage in the IM rod having an axis positioned at an angle relative to the longitudinal axis of the IM rod such that the axis of the sleeve is directed toward the head of the femur. The IM hip screw is described as permitting sliding compression of selected fractures, particularly intertrochanteric fractures and fractures of the femoral neck.
U.S. Pat. No. 6,443,954 to Bramlet et al., which is incorporated herein by reference, describes an IM system that includes a lag screw assembly extending through a radial bore in an IM nail.
U.S. Pat. No. 6,235,031 to Hodgeman et al., which is incorporated herein by reference, describes an IM system that includes an IM rod, a lag screw, and a lag screw collar.
U.S. Patent Application Publication 2002/0151898 to Sohngen et al., which is incorporated herein by reference, describes an IM nail having a modular configuration, including a nail member having a chamber formed on the proximal end thereof.
U.S. Patent Application Publication 2002/0156473 to Bramlet et al., which is incorporated herein by reference, describes an IM system that includes an IM nail for insertion in the femur. The nail has an axial bore and an intersecting transverse bore. A lag screw is inserted through the transverse bore and turned into the head of the femur. A slotted sleeve is inserted over the lag screw and through the transverse bore with the slots aligned with the axial bore. A sleeve lock is inserted into the axial bore, and has a locking tab which engages the slots in the sleeve preventing rotational and longitudinal movement between the sleeve and the nail. A compression screw is turned into the trailing end of the lag screw and engages the encircling sleeve to provide longitudinal translation between the lag screw and sleeve to apply compressive force across a fracture.
European Patent Application Publication EP 0 521 600 to Lawes, which is incorporated herein by reference, describes an IM system that includes an IM rod having an angulated opening to receive a femoral neck screw having a threaded portion at its distal end, and locking means acting between the neck screw and the wall of the angulated opening to prevent relative rotation between the screw and the rod.
PCT Publication WO 02/083015 to Ferrante et al., which is incorporated herein by reference, describes an orthopedic screw having a screw head, a screw body with a distal tip, a shank with an enlarged diameter at the trailing end and a thread extending radially outward from the shank, and an internal capture surface. The screw is used with an orthopedic implant system, which includes an orthopedic implant and a driver capable of engaging the internal capture of the screw.